code: def read_allocation_table(self):
      offset = self.header["alloc_table_ptr"]
      alloc_table = np.fromfile(
          self._fname, dtype=ALLOC_TABLE_TYPE, offset=offset
      )
      alloc_table.setflags(write=False)
      self.alloc_table = alloc_table
  
file_path: ffcv/ffcv/reader.py
imports: import numpy
  from .utils import decode_null_terminated_string
  from .types import ALLOC_TABLE_TYPE, HeaderType, CURRENT_VERSION, FieldDescType, get_handlers, get_metadata_type
label_desc: Use image node_id 6 for calling the Reader obj's underlying member method code with example usage: obj.read_allocation_table() without return types